I am not to sure if this is a question which fits the topics of software engineering.

I have two levels of objects "Categories" and "Category Values". I need to build a user interface for users to choose from that items and select as many as they want.

There can be like 10 or 20 Categories but each category can have from 1 to (worst case) 1000 category values.

For example:

• Type
• Image
• Document
• Priority
• High
• Low
• Medium
• City
• Cardiff
• ... + 999 more.

So to categorize certain items the user needs to choose from this list and needs to see what has been chosen so far.

I thought of a double select list but the list would be so long that it would involve a lot of scrolling (especcially with many category values). The same is for two trees because its only two level there is not much folding possibility.

What is the best way of giving letting the user make such a categorization ?

I am not to sure if this is a question which fits the topics of software engineering.

I have two levels of objects "Categories" and "Category Values". I need to build a user interface for users to choose from that items and select as many as they want.

There can be like 10 or 20 Categories but each category can have from 1 to (worst case) 1000 category values.

For example:

• Type
• Image
• Document
• Priority
• High
• Low
• Medium
• City
• Cardiff
• ... + 999 more.

So to categorize certain items the user needs to choose from this list and needs to see what has been chosen so far.

I thought of a double select list but the list would be so long that it would involve a lot of scrolling (especcially with many category values). The same is for two trees because its only two level there is not much folding possibility.

What is the best way of letting the user make such a categorization ?